JP4062269B2 - Synchronous rotating electrical machine - Google Patents

Description

  The present invention is in the technical field of a synchronous rotating electrical machine (including a synchronous motor, a synchronous generator, and a synchronous motor generator) in which a rotor rotates by the interaction between a magnetic field of a permanent magnet and a magnetic field generated by a multiphase coil. Belongs.

In the synchronous motor, as an example of setting the arrangement of the permanent magnets provided on the rotor to an unequal pitch, a plurality of permanent magnets are set to be shifted back and forth by 30 degrees in electrical angle. That is, assuming that the electrical angle of one pole pair is 330 degrees and the electrical angle of the other pole pair is 390 degrees, for example, an electromotive voltage generated in a U-phase coil has a phase difference between one coil and the other coil. The resultant voltage shifts back and forth, and the resultant voltage is not a rectangular wave, but has a portion that changes stepwise at its rise and fall. As a result, the electromotive voltage generated in each phase coil, and hence the inter-terminal voltage, approaches a sine wave, and the control characteristics and efficiency of the synchronous three-phase motor are improved (see, for example, Patent Document 1). .
JP-A-7-255159

  However, in the conventional synchronous motor, a large unequal pitch such as 30 degrees as an electrical angle and 15 degrees as a mechanical angle is set. There has been a problem that the electromagnetic force fluctuation of the order, that is, the high-frequency vibration excitation force of the stator cannot be reduced.

  The present invention has been made paying attention to the above problem, and an object of the present invention is to provide a synchronous rotating electrical machine that can reduce high-frequency electromagnetic excitation force of a stator that causes high-frequency noise.

In order to achieve the above object, the present invention comprises a stator having teeth around which a coil is wound, and a rotor having a permanent magnet, and interaction between the magnetic field of the permanent magnet and the magnetic field generated by a multiphase coil. In the synchronous rotating electric machine in which the rotor rotates by
When two of the permanent magnets are paired, an electromagnetic that acts on the teeth to excite the annular zero-order mode vibration in the stator with respect to a circumferentially uniform pitch arrangement between the permanent magnets in at least one pair. A synchronous rotating electrical machine characterized in that the setting is shifted by an angle that reduces the excitation force.

Therefore, in the synchronous rotating electric machine according to the present invention, the annular zero-order mode vibration is excited in the stator by acting on the teeth with respect to the circumferentially uniform pitch arrangement between at least one pair of permanent magnets. The setting is shifted by an angle that reduces the electromagnetic excitation force. Thus, for example, an n-order electromagnetic excitation force acting on the teeth due to the interaction of the magnetic field of another permanent magnet with respect to an n-order electromagnetic excitation force acting on the teeth due to the interaction between the input current and the magnetic field of a certain permanent magnet. Becomes an opposite phase and exhibits an action of reducing by canceling the n-th order electromagnetic excitation force. As a result, the high-frequency electromagnetic excitation force of the stator that causes high-frequency noise can be reduced.

  Hereinafter, the best mode for carrying out the synchronous rotating electrical machine of the present invention will be described based on Example 1 and Example 2 shown in the drawings.

  1 is an overall view showing a rotor and a stator of a synchronous three-phase motor (an example of a synchronous rotating electric machine) according to the first embodiment, and FIG. 2 is a synchronous three-phase motor incorporating the rotor and stator of FIG. It is sectional drawing which shows this structure.

First, the overall configuration of the synchronous three-phase motor will be described with reference to FIG.
This synchronous three-phase motor is a three-phase motor with distributed winding of 4 pole pairs and 48 teeth that tend to be frequently used to provide high output and low vibration characteristics. And a motor case 60 for storing the battery. The rotor 50 has permanent magnets 51 to 58 mounted on the outer peripheral portion thereof, and rotatably supports the rotating shaft 40 provided at the center of the shaft by bearings 61 and 62 provided on the motor case 60.

The configuration of the rotor 50 will be described with reference to FIG.
A laminated steel plate fixed by press-fitting with respect to the rotating shaft 40 is used as a base material, and eight permanent magnets 51 to 58 are fixed to the outer peripheral portion through the axial direction. The permanent magnets 51 to 58 are magnetized in the thickness direction, and every other N pole and S pole are arranged in opposite directions. When the rotor 50 is assembled to the stator 30, the permanent magnets 51 to 58 form a magnetic path due to the relationship between the permanent magnet of the rotor 50 and the electromagnet of the stator 30.

The configuration of the stator 30 will be described with reference to FIG.
A laminated steel plate fixed to the motor case 60 by press-fitting, bolting or the like is used as a base material, and a total of 48 teeth (1) to (48) are provided on the inner side facing the rotor 50. A coil 32 that generates a rotating magnetic field in the stator 30 is wound around a slot formed between the teeth (1) to (48). As shown in FIG. 1, the coil 32 is divided into a U-phase coil 32, a V-phase coil 32, and a W-phase coil 32, and each phase coil 32 is controlled by a controller (not shown). Connected to the motor driver. The rotor 50 of the synchronous three-phase motor can be rotated at a rotational speed corresponding to the frequency by applying an alternating voltage of a predetermined frequency different in phase by 120 degrees from the motor driver to the coil 32 of each phase. Rotate.

The arrangement of the permanent magnets 51 to 58 set on the rotor 50 at an uneven pitch in the circumferential direction will be described with reference to FIG.
In the first embodiment, as shown in FIG. 1, permanent magnets 51 and 55 are selected as a pair, and the 48th-order electromagnetic excitation force is reduced with respect to the circumferential uniform pitch arrangement (θ = 180 degrees in this example). In addition,
θ + 360 / (2 × n) degrees = θ + 3.75 degrees. However, n = 48.

Next, the electromagnetic excitation force reducing action will be described.
FIG. 3 shows the main modes of the stator that are problematic as high-frequency noise of the electric motor. In FIG. 3, the rotor and the like are omitted to display the vibration mode.
In FIG. 3, the electromagnetic force fluctuation | variation which generate | occur | produces with the permanent magnet of the rotor which is not shown in figure and the magnetic field of a multiphase coil acts on teeth as an electromagnetic excitation force (arrow of FIG. 3). As a result, as shown by the dotted line in FIG. 3, an annular zero-order mode (a mode with zero vibration nodes) is exhibited, and the vibration causes motor noise.

  As another vibration mode, FIG. 4 shows an annular sixth mode (mode with six vibration nodes). This circular sixth-order mode is a mode excited by an electromagnetic excitation force, similar to the circular zero-order mode in FIG. 3, but as shown in the dotted line in FIG. It is said that the efficiency of becoming a radiated sound is higher in the circular zero-order mode in FIG. 3 without unevenness than in the circular sixth-order mode in FIG. 4 with unevenness.

  The first embodiment reduces the electromagnetic excitation force that excites the circular 0th-order mode of FIG. 3 by reducing the n-order higher-order component that specifies the electromagnetic force fluctuation acting on each tooth, and as a result, the electric motor The purpose is to reduce high frequency noise.

Therefore, a synchronous three-phase motor having four pole pairs and 48 teeth in which permanent magnets are arranged at an equal pitch with respect to the rotor will be described as a comparative example (FIGS. 5 to 7).
As typical motor operating conditions, the electromagnetic force analysis result in the tooth (1) at a constant rotational speed is shown in FIG. 5, and the electromagnetic force analysis result in the tooth (2) at a constant rotational speed is shown in FIG.
The characteristic of the electromagnetic force acting on the teeth is always inward (direction attracted to the rotor side). As can be seen from FIG. 3, the electromagnetic excitation force that excites the circular zeroth-order mode can be evaluated by adding each of the teeth because they contribute substantially the same amount. FIG. 7 shows the result of Fourier analysis of the electromagnetic excitation force that excites the circular zero-order mode. In this example, the 24th order (24 times speed) and the 48th order (48 times speed) are higher than the other orders with respect to the rotational speed of the rotor.

  Here, the case where 48th-order electromagnetic excitation force is reduced is considered as an example. The 48th-order components of the teeth (1) and (2) are shown together with the electromagnetic force raw waveform in FIGS. This 48th-order component is reduced for each tooth.

  In the reduction method, the 48th-order electromagnetic excitation force generated in the teeth (1) due to the interaction between the input current and the magnetic field of a certain permanent magnet is generated in the teeth (1) due to the interaction between the magnetic fields of other permanent magnets. The 48th-order electromagnetic excitation force is reduced by shifting the phase by 180 degrees to the opposite phase and canceling it.

  As described above, in order to reduce the 48th-order electromagnetic excitation force, in the first embodiment, as shown in FIG. 1, the permanent magnets 51 and 55 are selected as a pair and arranged at a uniform pitch (in this example, θ = 180). Degree) was shifted by θ + 360 / (2 × n) degrees = θ + 3.75 degrees (where n = 48).

  FIG. 8 shows the 48th-order component of the electromagnetic force and the electromagnetic force raw waveform in the tooth (1) in the first embodiment. In FIG. 8, the 48th-order component of the electromagnetic force raw waveform is not a sine wave, but it can be seen that the electromagnetic force level is reduced as compared with FIG. 5 in which permanent magnets are arranged at an equal pitch.

  And the contrast characteristic of the electromagnetic excitation force characteristic which excites the circular 0th-order mode in Example 1 which was arranged with unequal pitch, and the electromagnetic excitation force characteristic which excites the circular 0th-order mode in the comparative example of uniform arrangement | positioning Is shown in FIG. As is clear from this comparison characteristic, a reduction allowance of about 2.4 dB was obtained as a 48th-order electromagnetic excitation force reduction effect.

  Similarly, although not shown in the drawings, as a modification of the first embodiment, the permanent magnets 51 and 54 are selected as a pair, and the circular zero-order mode is excited when shifted by θ + 3.75 degrees (in this case, θ = 135 degrees). FIG. 10 shows a contrast characteristic between the electromagnetic excitation force characteristic and the electromagnetic excitation force characteristic that excites the annular zero-order mode in the comparative example of the uniform arrangement. As is clear from this comparison characteristic, a reduction allowance of about 2.4 dB, which is almost the same as that in FIG. 9, was obtained as an effect of reducing the 48th-order electromagnetic excitation force.

Next, the effect will be described.
In the synchronous rotating electric machine according to the first embodiment, the effects listed below can be obtained.

  (1) A stator 30 having teeth (1) to (48) wound with coils and a rotor 50 having permanent magnets 51 to 58, which are generated by the magnetic field of the permanent magnets 51 to 58 and a multiphase coil. In the synchronous rotating electrical machine in which the rotor 50 is rotated by the interaction with the generated magnetic field, when two of the permanent magnets 51 to 58 are paired, the circumferentially uniform pitch between the permanent magnets in at least one pair Since the setting is shifted from the arrangement by an angle that reduces the electromagnetic excitation force acting on the teeth, the high-frequency electromagnetic excitation force of the stator 30 that causes high-frequency noise can be reduced.

  (2) When two of the permanent magnets 51 to 58 are paired, an integer multiple n of the rotational speed of the rotor 50 is used, and at least one permanent magnet in the pair has a uniform pitch in the circumferential direction. Since it is shifted by approximately ± 360 / (2n) degrees, it is possible to effectively reduce the electromagnetic excitation force that excites the circular zero-order mode, which is the largest cause of motor high-frequency noise.

  (3) The integer multiple n is set to an integral multiple (n = 24 × 2 = 48) of the least common multiple 24 of the number of phases 3 of the multiphase current input to the coil and the number of permanent magnets 8 of the rotor 50. Therefore, the high frequency noise which is a problem particularly in the synchronous three-phase motor having 4 poles and 48 teeth can be effectively reduced.

  The second embodiment is an example in which a pair of permanent magnets in the same pole pair is selected and the direction in which a plurality of permanent magnet pairs are shifted is unified.

  First, the configuration will be described. As shown in the 1/4 model of FIG. 11, in the case of a plurality of pairs, the permanent magnets 51 and 52 are selected as a pair of permanent magnets in the same pole pair, and are arranged at an equal pitch (in this example, θ + 360 / (2 × 48) degrees = θ + 3.75 degrees with respect to θ = 45 degrees).

  In the 1/4 model of FIG. 11, since symmetry conditions are given at 0 degrees and 90 degrees, the permanent magnets 53 and 54 shown in FIG. 1 constitute a pair, and the permanent magnets 55 and 56 are another pair, and The permanent magnets 57 and 58 also constitute another pair. That is, the four pairs are shifted by +3.75 degrees. Since other configurations are the same as those of the first embodiment, illustration and description thereof are omitted.

  Next, the operation will be described. FIG. 12 shows the calculation result of the electromagnetic force in the tooth (1) according to the second embodiment shifted by +3.75 degrees in each of the four pairs. FIG. 12 shows the electromagnetic force raw waveform and the 48th-order component of the electromagnetic force raw waveform. In the case of Example 2, it can be seen that the 48th-order component of the electromagnetic force raw waveform is further reduced as compared with the calculation result of the electromagnetic force in the tooth (1) of Example 1 in FIG.

  Electromagnetic excitation force characteristics for exciting the circular 0th-order mode in Example 2 shifted by +3.75 degrees in each of the four pairs, and electromagnetic excitation force for exciting the circular 0th-order mode in the comparatively arranged example FIG. 14 shows a contrast characteristic with the characteristic. As is clear from this comparison characteristic, a reduction effect exceeding 20 dB is obtained as a reduction effect of the 48th-order electromagnetic excitation force.

  In general, assuming that the order to be reduced is n, the nth-order electromagnetic excitation force of the permanent magnet with respect to the teeth can be reversed by shifting ± 360 / (2 × n) degrees with respect to the angle between the permanent magnets in the uniform arrangement. Ring zero-order electromagnetic excitation force can be reduced.

  Further, even when a plurality of pairs of permanent magnets are shifted as in the second embodiment, the rotation balance can be maintained if the shifting directions are unified.

  As a modification of the second embodiment, when the arrangement shifted with respect to a plurality of n (for example, n = 24, 48) is adopted, both the 24th-order electromagnetic excitation force and the 48th-order electromagnetic excitation force are reduced. Thus, the effect of reducing the electromagnetic excitation force is exhibited by superposition.

Next, the effect will be described.
In the synchronous rotating electrical machine of the second embodiment, in addition to the effects (1) to (3) of the first embodiment, the effects listed below can be obtained.

  (4) When there are a plurality of pairs of the permanent magnets 51 to 58, the pair is composed of the same pole pair. Therefore, by setting a circumferential unequal pitch for a plurality of permanent magnet pairs (four pairs), Compared to the circumferential unequal pitch setting for a pair of permanent magnets, the ring zero-order electromagnetic excitation force can be reduced more effectively.

  (5) Permanent magnets composed of a plurality of pairs composed of the same pole pairs have a uniform shifting angle of + 360 / (2n) degrees or -360 / (2n) degrees. Also, the rotation balance of the rotor 50 can be maintained.

  (6) Since a plurality of different integers 24 and 48 are used as the integer multiple n used for calculating the displacement angle of the permanent magnet, the 24th and 48th electromagnetic excitation forces can be superimposed on each other. Can be reduced.

  As described above, the synchronous rotating electric machine according to the present invention has been described based on the first embodiment and the second embodiment. However, the specific configuration is not limited to the first and second embodiments. Design changes and additions are permitted without departing from the scope of the claimed invention.

  In the first and second embodiments, the example in which the 48th-order electromagnetic excitation force is reduced is shown, but an example in which the 24th-order electromagnetic excitation force is reduced may be used. In this case, θ + 360 / (2 × 24) degrees = θ + 7.5 degrees.

  In the embodiment, as an example of the synchronous rotating electric machine, an example of a distributed winding synchronous three-phase motor with 48 poles and 48 teeth is shown, but the present invention is similarly applied to synchronous motors having different numbers of pole pairs, teeth and phases. In addition to the synchronous motor, the present invention can be applied to a synchronous generator and a synchronous motor generator.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an overall view showing a rotor and a stator of a synchronous three-phase motor (an example of a synchronous rotating electric machine) according to Embodiment 1; It is sectional drawing which shows the structure of the synchronous three-phase motor of Example 1 incorporating the rotor and stator of FIG. It is a figure which shows the ring 0th-order mode which becomes the main causes of noise. It is a figure which shows the annular | circular 6th-order mode as another vibration mode. It is a characteristic view which shows the electromagnetic force (calculation result) of teeth (1) in the case of uniform pitch arrangement. It is a characteristic figure which shows the electromagnetic force (calculation result) of teeth (2) in the case of uniform pitch arrangement. It is a figure which shows the influence (calculation result) of each rotation order with respect to circular 0th-order mode. It is a figure which shows the electromagnetic force (calculation result) of teeth (1) at the time of applying the non-uniform pitch arrangement | positioning of Example 1. FIG. FIG. 3 is a comparison characteristic diagram between the electromagnetic excitation force characteristic (calculation result) for exciting the circular zero-order mode in the first embodiment and the electromagnetic excitation force characteristic (calculation result) for exciting the circular zero-order mode in the comparatively arranged comparative example. It is. The electromagnetic excitation force characteristic (calculation result) for exciting the circular zero-order mode in the modified example of Example 1 and the electromagnetic excitation force characteristic (calculation result) for exciting the circular zero-order mode in the comparative example of uniform arrangement It is a contrast characteristic figure. FIG. 4 is a 1/4 model diagram illustrating a rotor and a stator of a synchronous three-phase motor (an example of a synchronous rotating electric machine) according to a second embodiment. It is a figure which shows the electromagnetic force (calculation result) of teeth (1) at the time of applying the non-uniform pitch arrangement | positioning of Example 2. FIG. Comparison characteristic diagram between electromagnetic excitation force characteristic (calculation result) for exciting circular zero-order mode in Example 2 and electromagnetic excitation force characteristic (calculation result) for exciting circular zero-order mode in a comparative example of uniform arrangement It is.

Explanation of symbols

30 Stator
(1)-(48) Teeth 32 Coil 40 Rotating shaft 50 Rotor 51-58 Permanent magnet 60 Motor case 61, 62 Bearing

Claims (6)

In a synchronous rotating electrical machine including a stator having teeth around which a coil is wound and a rotor having a permanent magnet, and the rotor rotates by the interaction between the magnetic field of the permanent magnet and the magnetic field generated by a multiphase coil ,
When two of the permanent magnets are paired, an electromagnetic that acts on the teeth to excite the annular zero-order mode vibration in the stator with respect to a circumferentially uniform pitch arrangement between the permanent magnets in at least one pair. A synchronous rotating electrical machine characterized in that the setting is shifted by an angle that reduces the excitation force. In the synchronous rotating electrical machine according to claim 1,
When two of the permanent magnets are paired, an integer multiple n of the rotational speed of the rotor is used, and at least ± 360 / (2n) with respect to the circumferential uniform pitch arrangement between the permanent magnets in at least one pair. Synchronous rotating electrical machine characterized by being shifted by degrees. In the synchronous rotating electrical machine according to claim 2,
A synchronous rotating electrical machine characterized in that the integer multiple n is defined as an integral multiple of the least common multiple of the number of phases of the multiphase current input to the coil and the number of permanent magnets of the rotor. In the synchronous rotating electrical machine according to any one of claims 1 to 3,
When there are a plurality of pairs of the permanent magnets, the pairs are constituted by the same pole pair. In the synchronous rotating electrical machine according to claim 4,
A synchronous rotating electrical machine characterized in that the permanent magnets of a plurality of pairs configured with the same pole pair are unified at a shift angle of + 360 / (2n) degrees or -360 / (2n) degrees. In the synchronous rotating electrical machine according to claim 4 or 5,
A synchronous rotating electric machine characterized in that a plurality of different integers are used as an integer multiple n used for calculating the shift angle of the permanent magnet.

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